Gas-purification process



C. J. RAMSBURG.

GAS PURlFiCATION PROCESS. APPALICATION FILED DEc.s,1921.

combined with a revivification of the ab' avoided.

' urposes of exemplificationv a maaier glar stica,

CHARLES J'. RAMSBURG, 0F PITTSBURGH,

PENNSYLVANIA, -ASSIGNOR T0 THE KOFFER@ COMPANY, 0F PITTSBURGH,PENNSYLVANIA,

A CORPORATION OF PENNSYLVANIA.

eas-Puarrica'rion rnociess.

Application led December 8 1921. Serial No. 520,781.

'To all whom t comer/n.:

Be it known that I, CHARLES JLRAMS- BURG, siding in Pittsburgh,in thecounty of Allegheny and State of Pennsylvania, have" in'- vented a newand useful Improvement in Gas-Purification Processes, of which thefollowing is a specification.

This invention relates to the removal of hydrogen sulphide and othernoxious constituents, such as hydroc anic acid, from gases containingthem. vention are to effect an ecient purification of the gases by meansof anabsorbent liquid which removes the noxious constituents,

sorbent liquid by a subsequent treatment that removes` substantially allthe absorbed sulphur in a solid form, wherebythe escape of noxious fumesinto the atmosphere in the vicinity of the gas` -purifying plant is Inaddition to they general objects recited above, the invention has forfurther objects such other improvements or advantages in operation andresults as are found Ato obtain in the processes hereinafter describedor claimed f In the accompanying drawing, forming a part of thisspecification and showin for re erred orm and manner in which theinvention maybe embodied and practiced but without limiting the claimedinvention specifically to such illustrative instance:

The figure illustrates a diagrammatic rep# resentation of apparatus forcarrying out the improved gas purifying process of the l is applic mentherein i moved, are brought present invention. In its presentembodiment,the invention to the purification of fuel gases,

such as coke oven gas; for convenience', the present description willimportant application ofthe invention. Features of the invention are,susceptible of othervaluable applications; consequently, the inventionis not confined in itsA scope to the specific use and embodidescribed asan illustrative example.

In carrying out the invention, the gases,-

after the tar andv ammonia have been reinto contact with an absorbentagent constituted of a purifying Solution which is y alkaline inreaction, for

a citizen of the nited States, re

bjects of the in.

be confined to this however, readily :and free sulphur.

cent solution o sodium carbonate will be found satisfactory.. The gasesto be puriiied enter the bottom of the scrubber or y washer A through agas line 1 and discharge t e from the top of said scrubber throughpurified gas-line 2. The purifying solutionv is delivered tothe top ofthe scrubber A through the solution line 3 and the solution containingthe absorbed impurities discharges from the bottomv of said scrubberthrough a line 4 into a foul solution tank or sump 5.v In the scrubber,the* solution absorbs the hydrogen sulphide and kother noxiousconstituents of the gases, forming soluble sulphide compounds, such assodium hydrogen sulphide. Carbon dioxide if present in the gas, is alsoabsorbed.

The resulting foul solution yis passed from the tank 5 through a line 6into a mechanical agitator B in which said solution is brought intointimate contact with hydrated iron oxide, with the result that asuspension ,of iron oxide is formed in the solution. Be-

voriginal state. The concentration of the iron oxide in the suspensionin the agitator may be varied as desired; 1n practice,

however, a twoor three per cent suspension of iron oxide will be foundsatisfactory., ,Various iron compounds may be emloyed for this purpose,as stated later, but

. in the present exempliiication reference is 'made to iron oxide only.

The mixture of regenerated -alkali solution and iron sulph1de is thenpumped through a line 7 into a continuous separator C,such as a Dorrthickener, resultin in a separation of the iron sulphide as a eavysludge from the clear alkaline liquor.- The thick 4iron sulphide sludgeis pumped through a line 8 into a tank D where it is aerated and therebconverted to iron oxide he regenerated iron oxide and free sulphur maybe pumped through a line 9 back to the agitator B to treat furtherquantities ofl foul alkaline liquor from `the absorber A. Theregenerated alkaline solution discharges from the. Dorr thick- DEScarried aerating treatment, to remove any residual The alkalinesolutionis ,then to the absorber A tolpuri'f. more gas, and 'may bestored in a tank l1 or--besulphur.

ving pumped back to the said scf-rubber. The

Whole process may be made continuous by carrying it out as abovedescribed and in the manner illustrated inthe diagram of the apparatus.

lf desired, the thick iron sulphide sludge from the Dorr thickener C orseparator may be filter-pressed and washed before aerating.

Mechanical eiiciency-of the process is assured by using a clear solutionin the scrubber Where the gas has to be handled. The steps in theprocess which 'mvolve the iron oxide suspension in the solution are allthey can be conveniently performed.

The chemical reactions taking lace in the absorption stage.; may beexemplied by the following equations: y (a) Absorption of hydrogensulphide by sodium carbonate:

(if) 'Carbon sorbed Negoc.,Jfno+co2=2uanoo3 (c) Hydrocyanic acid, ifpresent, is also absorbed:

na,ooa+nou=uaou+mnoo3 The chemical reaction in the agitator may beexemplified by the followingequation:

Conversion of iron oxide to iron sulphide and' regeneration of thealkali:

lBy aerating the clear alkaline liquor, sodlum bicarbonate is convertedto carbonate, according to the following equation:

The free sulphur may be be accumulated in the suspension of .iron oxide,part of the sludge being Withdrawn at suitable times for the recovery.of the sulphur and iron oxide. From time 'to time, fresh iron oxide isadded; or else iron sulphide may be added at a point before the willconvert it to iron1 dioxide, if present, is also aboxide. The concenoutoutside of the scrubber Where 4 sulphide to iron oxide.

pconsists in air treatment which tration of dissolved alkali in thesolution is also mai;.ta'ined rby periodical additions.

The chemical reaction in the agitator can be carried out with iron oxidein suspension, or instead of iron oxide, other ferrie compounds may beused Which have essentially the same action, namely such compounls asferrie carbonate, basic ferrie carbonate, ferric oxide, or ferrouscompounds of iron. The solution used in the absorber may contain anysoluble alkaline substance, such as the carbonates or hydroxides ofsodium and potassium. The solution will remove hydrocyanic4 acid fromthe gas; the hydrocyanic acid may-go into chemical combination with theiron compounds, or else may pass .out to some extent With the air usedin the aerating process.

What is claimed is: l v 1 l. The process of purifying gases whichconsists in: passing the gas. into contact Withl an absorbent solutionconstituted of dissolved alkali to absorb sulphur from the gas; thenbringing the solution containing the absorbed impurities into contact'with a reaction occurs in which sulphur is transferred from the alkalito the iron, with formation of iron sulphide; then separating o ut theiron sulphide from the rejuvenated solution and subjecting the ironsulphide to aeration t0 remove the iron to its original state; andemploying the rejuvenated alkali solution for further gas purification;substantially as specified.

2. The process of purifying gases Which consists in: passing the .gasinto contact with an absorbent solution constituted of dissolved sodiumcarbonate' to absorb sulphur from the gas; then bringing the' solutioncontaiming the absorbed .impurities into contact with a vsuspension ofanxiron compound Whereby a reaction occurs in Which the sulphur istransferred from the sodium carbonate to the ironwith formation of ironsulphide; then separating out the iron sulphide `from the rejuvenatedsolution and sub- `looting the iron sulphide t0 aeration to remove thesulphur and restore the iron to its original state; and employing there- .j'uvenated sodium carbonate so ution for further gasy purification,substantially as specified; 3. The process of purifying gases whichpassing the gas v into contact with an absorbent solution constituted ofdissolved alkali to absorb sulphur from the gas; then bringing thesolution containing the absrn'bedV impurities into contact with asuspension of an iron oxide whereby a reaction occurs in which sulphuristransferred the sulphur and restore enq iso

to remove the sulphur and restore the iron to its original state; andemploying the rejuvenated alkali solution for further gas purification;substantially as specified.

4. The process of -purifying gas which consists in: passingv the gasinto vcontact with an absorbent -solution constituted of dissolvedalkali to absorb sulphur from the gas; then bringing the solutioncontaining lofthe absorbed impurities into contact withl an ironcompound, whereby a reaction occurs in which sulphur is transferred fromthe alkali to the iron, with formation of iron sulphide; returning therejuvenated alkali solution to the gas purification step; and subjectingthe iron sulphide to aeration to remove the-sulphur and restore the ironto its original state; substantially as specied. CHARLES J. RAMSBRG.

